Question:
In a typical Indian Bugghi (a luxury cart drawn by horses), a wooden plate is fixed on the rear on which one person can sit. A bugghiof mass $200 \mathrm{~kg}$ is moving at a speed of $10 \mathrm{~km} / \mathrm{h}$. As it overtakes a school boy walking at a speed of $4 \mathrm{~km} / \mathrm{h}$, the boy sits on the wooden plate. If the mass of the boy is $25 \mathrm{~kg}$, what will be the new velocity of the bugghi?
Solution:
C.O.L.M (conservation of linear momentum)
$m_{s} v_{s}+m_{b} v_{b}=\left(m_{b}+m_{s}\right) V$ s-school boy, b-bugghi
$V=\frac{200 \times 10+25 \times 4}{225}=\frac{28}{3}=9.3 \mathrm{~m} / \mathrm{s}$